MDO3000 Programmer Manual.pdf - 第78页

Command Groups 4. RF A verage tr ace: Data from the RF Normal t race is averaged over multiple acquisitions. This is true power aver aging, which occurs before the log conversion. Each power of 2 average reduc es the d i…

Command Groups

Table 2-36: Power Commands (cont.)

Command Description

POWer:SWLoss:TOTal:ENERGY:

MIN?

Returns the minimum total energy switching loss calculation

POWer:SWLoss:TOTal:POWer:

MAX?

Returns the maximum total power switching loss calculation

POWer:SWLoss:TOTal:POWer:

MEAN?

Returns the mean total power switching loss c alculation

POWer:SWLoss:TOTal:POWer:MIN?

Returns the minimum total power switching loss calculation

POWer:SWLoss:VCEsat This command speciﬁ es VCESAT value for use in switching loss calculations when the

conduction calculation method is VCESAT

POWer:TYPe This command speciﬁes the power application measurement type

POWer:VOLTA GESOurce This command speci ﬁes the voltage source for the power application

RF Command Group

The Tektronix MDO4000/B Series Oscilloscope models, MDO4000C models with

option SA3 or SA6, and MDO3000 models have a built-in RF input, in addition to

analog and digital channels, which allows you to display, measure, performmath

on and analyze both time and frequency domain signals with one instrument.

The MDO4000/B and MDO4000C models with option SA3 or SA6 combine

the fun

ctionality of a mid-range oscilloscope and a standard spectrum analyzer,

which makes it able to provide several time-correlated display and measurement

options for RF traces.

The MDO3000 allows frequency domain measurements but does not offer

time-correlated display and measurement options for RF traces.

The RF commands are concentrated in the RF Command Group, but also appear

in other command groups, including Save and Recall, Waveform Transfer, Trigger

and Search. A table is available that links the RF features to their corresponding

commands, regardless of command group. (See page 1-2, New or Changed

Functionality Updates that Impact the Programmatic Command Set.)

Frequency Domain Trace

Types

The MDO4000/B/C and MDO3000 support four frequency waveform types:

The frequency domain window provides support for four spectrum traces, which

may be turned on and off independently.

1. RF Normal trace: Each acquisition is discarded as new data is acquired.

2. RF Max Hold trace: The maximum data values are accumulated over multiple

acquisitions of the RF Normal trace.

3. RF Min Hold trace: The minimum data values are accumulated over multiple

acquisitions of the RF Normal trace.

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-47

Command Groups

4. RF Average tr

ace: Data from the RF Normal trace is averaged over multiple

acquisitions. This is true power averaging, which occurs before the log

conversion. Each power of 2 average reduces the displayed noise by 3 dB.

Time Domain Trace Types

The MDO4000/B/C offers three additional time domain trace types in addition to

the usual analog and digital waveforms one expects on an oscilloscope. On these

instruments, the time domain window can also display three RF time domain

traces derived from the time-domain I&Q data acquired for the RF input. Theyare

time-correlated with the analog and digital channels, and represent a continuous

time domain data stream. The time domain trace options are:

1. The RF Amplitude vs. Time trace: The instantaneous amplitude of the input,

after band-pass ﬁltering, relative to the current frequency range (as deﬁnedbythe

center frequency and span settings.)

2. The RF Frequency vs. Time trace: The instantaneous frequency of the input,

relative to the center frequency. The vertical axis displays frequency. The

frequency versus time waveform handle (baseline indicator) indicates thecenter

frequency. When the trace is above the waveform handle, it is above the center

frequency. When the trace is below the waveform handle, it is below the center

frequency.

3. The RF Phase vs. Time trace: The instantaneous phase of the input, relative to

the center frequency. The vertical axis displays phase, with wrapping at roughly

+/- 180°.

The squelch function is used to suppress the phase and frequency information

when the amplitude of the RF input is below a user-speciﬁed value. This keeps

both the RF Frequency vs. Time and the RF Phase vs. Time traces from displaying

broad bands of noise when there is no signal present on the RF input.

Time-Correlated

Multi-Domain Display

(MDO4000/B and MDO4000C with option SA3 or SA6 only.)

A single trigger event coordinates acquisition across all analog, digital, and

RF inputs. This enables a time-correlated view of both the time and frequency

domain signals in a single instrument.

Spectrum Time: This is the period of time used to calculate the spectrum shown

in the frequency domain graticule.

Analog Time: This is the amount of time acquired in the time domain graticule.

RF Acquisition Time: This is the amount of time acquired by the RF system. At

mid-to-fast time base settings, it equals analog time. At slower time base settings,

it can be less than analog time.

Acquisition Stages

RF acquisitions travel through their own signal path before being digitized by the

oscilloscope. This signal path includes a combination of analog ampliﬁcation,

2-48 MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual

Command Groups

attenuation, ﬁ

ltering and down-conversion, depending on the parameters set by

the user (frequency, span, reference level, and so forth.)

For the MDO400

0/B/C series models, the acquisition system uses one of three

frequency bands to acquire RF data depending on where the center frequency and

span are set. The bands are: 50 kHz to 3.75 GHz, 2.75 GHz to 4.5 GHz, and

3.5 GHz to 6.0 GHz.

For the MDO3000 series models, there is one frequency band (up to 3 GHz

depending on the model and installed options).

Specifying the Reference

Level and Resolution

Bandwidt

h (RBW) Settings

For the MDO4000/B/C series models, the reference level is adjustable from

–140 dBm to +30 dBm. For the MDO3000 series models, the reference level

is adjustable from –140 dBm to +20 dBm. For all series, attenuation is set

automatically with the reference level. The RBW setting is adjustable downto

20 Hz. By

default, the RBW tracks span in automatic mode in a 1000:1 ratio;

this ratio is adjustable.

Detection Types

All MDO instruments calculate Fast Fourier Transform calculations (FFTs) with a

1,000 t

o ~2,000,000 point output, depending on the acquisition settings. It then

reduces that FFT output into a 1,000 pixel-wide display (for the MDO4000/B/C)

or 750 pixel-wide display (for the MDO3000). This means that approximately

1 to 2,000 FFT points get compressed into each pixel column. There are four

choices as to how this compression is done: +peak, sample, average, and -peak.

TriggeringUsingRFPower

Level as a Source

You can use the RF power level as a source for triggering with the MDO4000/B/C

models (but not the MDO3000 models). The MDO4000/B/C triggered acquisition

system is fully integrated with both the frequency and time domains. This means

that a single event can trigger all of the analog, digital and RF acquisitions,

gardless of whether that event came from an analog, digital or RF input. The

RF power level has been distilled through special processing and may be used

as a trigger. RF Power may be used as a source for Edge triggering. With an

MDO4TRIG application module installed, the RF Power level can also be used as

a source for pulse width, timeout, runt, logic and sequence triggering. (For more

information, see Triggering on the RF input. (See page 2-76, Trigger Command

Group.)

Spectrogram Display

(MDO4000/B, MDO4000C with option SA3 or SA6, and MDO3000). The

spectrogram is a graph of frequency domain traces over time. It provides an

intuitive display that is useful for monitoring slowly changing RF events,and

for identifying low amplitude signals too subtle for the eye to catch in a regular

spectrum display. The x-axis shows frequency, and the y-axis shows time.

Amplitude is represented by the color of the trace. Cold colors (blue, green)

indicate low amplitude, and hot colors (red, yellow) indicate high amplitude.

MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-49